This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In the absence of an effective vaccine, other methods for preventing the sexual transmission of human immunodeficiency virus type 1 (HIV-1) must be pursued. Recently, increased attention has been placed within the wider vaccine research field on the notion that non-neutralizing Abs may protect against HIV-1 transmission, and should therefore be induced by a vaccine. To investigate this hypothesis in a more definitive manner we are administering monoclonal antibodies derived from HIV patients that do not neutralize (provided by Dennis Burton) vaginally to macaques and challenging them with SHIV 30 min after challenge. We have performed two pilot studies but to date, these antibodies have failed to protect against vaginal SHIV challenge.